RG Index FAQ

Why a new ranking at all?
We have identified several significant weaknesses in the "old" ranking. First, the focus on the pure final position in a tournament (especially in systems like double knockout) does not necessarily fairly reflect the performance of the team over the course of the entire tournament. In addition, adding up points primarily rewards players who participate in many tournaments. Due to the Corona pandemic and especially the extreme rush at tournaments, we unfortunately cannot expect all players to be able to play in all tournaments. Therefore, from our point of view, we need a system that does not reward the quantity of tournament participations, but above all the quality, i.e. the performance in each individual game.

What is the difference between the old and the new ranking?
The new ranking is no longer defined by an addition of points for a certain performance in a tournament, but the socalled RG Index (Roundnet Germany Index, RGX for short). The biggest difference is that every single match within a tournament is used to calculate the RG Index.

What is the RG Index (RGX for short)?
The RG Index is a statistical value that calculates and reflects the playing strength of a player. It is based on the results of all individual matches that this player has played in tournaments from the year 2021 onwards (for a more detailed explanation, see the question "which results are used as a basis?"). For each match, both the playing strength of the own team and that of the opposing team are included (for a more detailed explanation, see the question "How are the points calculated?").

What tournament results are included in the RGX?
For the calculation of the RG Index we use all tournaments registered as a TourStop or Masters within the German Roundnet Tour from the year 2021 in the categories Women, Men and Mixed as well as the German Nationall Championships. From the 2023/2024 season, the games of the German Roundnet League will also be included in the RGX.

How are the points (is the RG Index) calculated?
Now it gets a little (very) mathematical. Basically, the formula calculates the average expected result for each individual game based on the RGX and compares it to the actual result. We'll go through two examples for this.
Since Roundnet is a team sport, the individual scores of the players are added together and form the RGX of the team. This ensures that games with different partners can be included in the RGX. The RGX of the two teams determined in this way are compared in each match to determine the point gains / losses for all players on the basis of the match result. The formula used provides a result for the team, this value is halved and credited/subtracted for both players.
Example A: In a game of a team B with a high RGX (e.g. 1300 per player) against a team A with a low RGX (e.g. 1000 per player), it is assumed that the "favorite team B" wins about 9 out of 10 games (average expected result e = 0.9, see formula below).
Victory Team B: If team B wins, "favorite team B" receives points (and the losing team loses some), but comparatively few, since the result played corresponds to the anticipated result (actual result p = 1, see formula). p is evaluated either as a win (1), a draw (0.5) or a loss (0). Thus, if p with a value of 1 is virtually equal to e with 0.9, there are few points in either direction.
Victory Team A: If the "favorite team B" again loses surprisingly (p with value 0 ≠ e with value 0.9), it loses significantly more points (and the surprisingly winning team A receives many).
Draw: Also a draw (e.g. in the preliminary round at 2 sets) can cost or bring points to a team, if this deviates from the expected result. In our example, the "favorite team B" loses points due to the draw. Since p differs by 0.5 from e by 0.9, but not as much as before, the loss or gain of points is less than if team A wins.
In a Best of 3/Best of 5:
The calculation of the RGX is adjusted so that the points in the "Best of 3" mode are no longer distributed with p =[0, 0.5, 1], but with p=[0, 0.33, 0.5, 0.67, 1]. Similarly, for a "Best of 5" in its different constellations, the points are distributed with p=[0, 0.25, 0.4, 0.6, 0.75, 1].
What changes now: The new intermediate levels lead to the fact that the actual result with a 2:1 is evaluated with 0.67, respectively 0.33 (instead of 1 and 0). So the "70% Team 1" loses some (few) points in case of a 2:1. The actual result of the match (from team 1's point of view) is 0.67, but the expected result is 0.7, therefore team 1 (0.67  0.7) gets k (minus) points. These inserted intermediate steps reduce the variance in the calculation, because game results are closer to the expected value more often than with the "all or nothing" calculation. Accordingly, in the "Best of 5" a 3:2 will be evaluated with 0.6 or 0.4 and a 3:1 with 0.75 or 0.25.In general, the closer the two RGXs of the teams are to each other, the closer the point values that a team can win or lose are to each other, since (apart from a draw, see below) there is always a relatively large difference between p and e of 0.5. If both teams have an identical RGX, all players can either win or lose 10 points.
Example B: In a game of two teams A and B with equal RGX (e.g. 1150 per player), it is assumed that both teams win exactly 5 out of 10 games or draw if possible (average expected result e = 0.5, see formula below).
 Victory of a team: Accordingly, a victory of a team that was not statistically expected (or at least the direction was not) results in a relatively large increase in points for the winning team (but a smaller one than in example A 2, where team A surprisingly beats the favorite team B).
 Draw: For the two statistically equally strong teams and the perfect factor e = 0.5, the situation can theoretically arise that in the case of a draw with the factor p = 0.5 there is no change at all for the index of all players involved, since p = e. However, this is rarely to be expected in practice.
For the mathematicians and statisticians among you, here is the calculation basis:
For those of you who are interested, we would of course like to communicate the correspondingly adjusted formula behind the calculation. This differs from the previously used only by the changed parameters. Only for the gradation of 1set games a new constant b is inserted:
With:
d = 550
k=50
b [0.75, 1] (1 if Bo3; 0.75 if 1set game)
p [0, 0.25, 0.33, 0.4, 0.5, 0.6, 0.67, 0.75, 1] (match result from team 1's point of view; 0 if 0:1/0:2/0:3; 0.25 if 1:3; 0.33 if 1:2; 0.4 if 2:3; 0.5 if 1:1/2:2; 0.6 if 3:2; 0.67 if 2:1; 0.75 if 3:1; 1 if 1:0/2:0/3:0)
r1 = previous score team 1
r2 = previous score team 2
e1 = calculated expected value for team 1
x1 = calculated point gain/loss for team 1
We have built you an index calculator so you can test the whole thing yourself (https://playerzone.roundnetgermany.de/ranking/calculator/).

Can I lose points with a win / gain points with a loss?
Yes, because in a "Best of 3" or "Best of 5" each set counts. This results in the possibility (also desired by you) that strongly favored teams could make minus points even with a 2:1, 3:1 or 3:2 win, but an "underdog team" can win points for a set win despite losing the whole match. A 2:0/3:0 and a 1:1/2:2 will be evaluated in the same way as before.

How can I collect points in the new ranking (increase my index)?
Very simple: Play tournaments and win games. Due to the fact that every game counts, in every tournament game you have the possibility to increase your index, but of course also the risk that it will decrease. However, you are no longer dependent on playing as many tournaments as possible to rise in the ranking.

How many tournaments do I have to play to get points (to change my index)?
Already one tournament with at least 5 games played (and that is the requirement to become a RG Tourstop anyway) is enough to improve (or worsen) your index. To guarantee a certain significance of the ranking, you need at least 15 games to be displayed in the table.

With which value do new players start in the ranking?
The starting value of a player is determined by the division at the first tournament  so there are different starting values for Beginner, Intermediate, Advanced and ProDivisions (qualification necessary). Players who start with a tournament without division (e.g. German Championships or tournaments before division introduction in April 2022) start with a default value of 1,300 points (average of all divisions). This mitigates problem 1: If you start new in Intermediate, you gain (or lose) about the same amount of points as before (because the difference to your teammates stays about the same). Due to the lower starting score, however, it takes a little longer to catch up with or overtake the players in the lower Advanced range. In addition, the special case of mostly foreign Advanced and Pro players, who play their first GRT tournament and would be clearly undervalued with the former standard starting value of 1,000 points, is handled.
Until now: In all divisions the starting value is 1,000 points.
New:
 Beginner: 1.000
 Intermediate: 1.200
 Advanced: 1.400
 Pro: 1.600 [currently only applies to (foreign) players who qualify for the Pro Division according to the tournament rules] Player with ProStatus always start with 1600 in their first tournament.
 ohne Division: 1.300
Info: The Beginner/Intermediate combo division is treated as Intermediate, Advanced/Pro as Advanced.
RGX points for the matches of the first tournament of a player are calculated twice with the formula. In the first run, the starting value per division is used for calculation. The result of this run will then be used as the actual base value (this one s also displayed in the player zone in the overview) for the player and thus a second run will be calculated.Note: This procedure inevitably leads to the fact that the results in the first tournament have a higher influence on the RGX.

What is the maximum number of points I can win/lose in a match?
The point gain and point deduction varies depending on the point difference. The maximum value for this is 25 per player per game and is reached when the point difference between the teams is at least 1,000 points and the underdog team wins the game. At the same time, the minimum possible point increase of 0 is also given here, namely if the favored team wins the game.

How are the different divisions rated?
The different divisions (Beginner, Intermediate, Advanced/Pro) are rated the same. The system itself calculates the strength of the opposing teams into the index, so a different rating is not necessary. In an Intermediate tournament, victories bring less points for the index, because the opposing teams are statistically rated lower than in Advanced/Pro tournaments. Therefore, there is a certain statistical limit in the index, which cannot be exceeded by only participating in Intermediate tournaments. Accordingly, the goal must be to attack at the next higher division.
The only requirement is that  regardless of the division  it must be in the men's, women's or mixed categories. Open tournaments are excluded from the calculation of the index! In addition, the person must fulfill the starting requirements to enter the division.

Why can't Open tournaments be included in the calculation, but Mixed can?
The purpose of open tournaments is to allow teams with different gender compositions to meet (e.g. 2 men vs. 2 women). However, these teams have previously earned their respective indices based on tournaments with the same gender composition (e.g. women, men or mixed). The indices of the two teams are therefore not comparable with each other; an equal index cannot be equated with an equal playing strength. In mixed tournaments, the different indices and playing strengths of the respective players balance each other out, since the composition is always the same, so that these can be included in the calculation.

Is there a minimum or maximum value that can be achieved?
Theoretically no, in practice most players will settle at a certain value after a certain time, because games are won and lost again and again. For the top players, there will be a certain stagnation at a high level, because they can hardly gain any more points due to their own very high RGX. On the other hand, with a very low RGX, you can hardly lose any more points at some point, so that there is no fixed minimum towards the bottom, but a certain stable range.

How will my index change if I don't play tournaments?
First of all, not at all. If you do not play, no new calculation bases for your index are added. However, so that nobody can "rest" on his own index, the index of a person is downgraded staggered after certain periods without tournament participation:
 9 months of inactivity: 10% on the score above the minimal start value 1,000
 12 months of inactivitiy: hiding from the ranking
 15 months of inactivity: 10% on the score above the minimal start value 1,000
 18 months of inactivity: reset all points to "0"  the playing person will be rated as a new player in the next tournament and will start with the corresponding starting value of the division.
Example: A person with a RGX of 1500 does not play a tournament for 9 months. Thus, this person loses 10% of the score above the minimum starting value of 1.000, i.e. 10% of 500 points = 50 points and thus drops to a value of 1450. After 15 months, 10% of 450 is subtracted, i.e. 45 points to a RGX of 1405.
This is to prevent that a person who has not played a tournament for a year, for example, and has presumably also lost in playing quality, is "overrated" due to results far away in time.

Is it relevant how high I win games?
Yes, but only a set win counts. The number of points per set is not relevant.
The calculation of the RGX is adjusted so that the points in the "Best of 3" mode are no longer distributed with p =[0, 0.5, 1], but with p=[0, 0.33, 0.5, 0.67, 1]. Similarly, for a "Best of 5" in its different constellations, the points are distributed with p=[0, 0.25, 0.4, 0.6, 0.75, 1].
What changes now: The new intermediate levels lead to the fact that the actual result with a 2:1 is evaluated with 0.67, respectively 0.33 (instead of 1 and 0). So the "70% Team 1" loses some (few) points in case of a 2:1. The actual result of the match (from team 1's point of view) is 0.67, but the expected result is 0.7, therefore team 1 (0.67  0.7) gets k (minus) points. These inserted intermediate steps reduce the variance in the calculation, because game results are closer to the expected value more often than with the "all or nothing" calculation. Accordingly, in the "Best of 5" a 3:2 will be evaluated with 0.6 or 0.4 and a 3:1 with 0.75 or 0.25.In order to be able to understand the different cases more exactly, you can play through the most different cases in our RGX Calculator and understand the point allocations: https://playerzone.roundnetgermany.de/ranking/rgindex/calculator/.

Is the index maintained throughout the tournament?
Yes, you enter the tournament with the index you have at that moment. The system does not automatically calculate your new index after each game entered on the Player Zone. So the recalculation of the RGX always takes place afterwards for all results of the tournament bundled. But you can see afterwards which game in the tournament brought you or cost you how many points.

What happens if I cannot continue playing due to injury or voluntarily do not compete?
In the case of an injury, as before, all subsequent matches will be counted as a loss in order to determine a final ranking in the tournament. For the evaluation of the index, however, only the match in which the injury occurred will be considered a defeat. Following games are of course not calculated  also for the "victorious" opposing team  because this would lead to an unfair distortion of the values. Nonattendance due to injury will be noted by the tournament organizers and forwarded to us.
In case of a voluntary nonappearance while the other team wants to play, the match will be considered as a defeat and will also be used for the calculation of the RG Index.

Will the old ranking be deleted? Why two rankings in parallel?
After the RG Index (RGX) was successfully introduced in a pilot stage in 2022, we have decided to continue the RGX as a ranking in 2023. In the future, it is planned to introduce additional features based on the RGX besides the division limits, e.g. a group stage with the help of a seed list by RGX score. These and other features are intended to gradually objectify the tournament system and make it as fair as possible.
In order to position a team in the RGX ranking depending on their playing strength, a high amount of games is needed. If a team has played only a few games, the RGX is partly not representative. For this reason there is still the GRT ranking, which is used e.g. for the qualification for the German Nationals.

Who can collect points?
Everyone who plays in a GRT ranking tournament regardless of country or playing division.

For which period is the RGX valid?
There is no time limit, the RGX is a continuous ranking.

Why are the division limits currently so generous?
The choice of upper and lower limits is intended to strike a balance between a sensible restriction of the divisions and the undesirable effect of players being "wrongly" excluded from a division. The concrete numbers are chosen in such a way that only the really clear cases are affected (e.g. "weaker" Intermediate players when registering in Advanced). For most players, therefore, this first introduction of lower limits does not yet change anything in practice and personal selfassessment will continue to play a major role. Due to the problems in RGX described above, there is a considerable number of Advanced players who still have relatively few points. We would like to continue to enable them to play in Advanced. For the future, however, it is planned to regularly analyze and, if necessary, adjust these upper and lower limits, so that the limits tend to become narrower and narrower and you have to "play" your way up to the next higher division.

Why do upper & lower divisions overlap so that you can compete in multiple divisions?
The choice of upper and lower limits is intended to strike a balance between a sensible restriction of the divisions and the undesirable effect of players being "wrongly" excluded from a division. The concrete numbers are chosen in such a way that only the really clear cases are affected (e.g. "weaker" Intermediate players when registering in Advanced). For most players, therefore, this first introduction of lower limits does not yet change anything in practice and personal selfassessment will continue to play a major role. Due to the problems in RGX described above, there is a considerable number of Advanced players who still have relatively few points. We would like to continue to enable them to play in Advanced. For the future, however, it is planned to regularly analyze and, if necessary, adjust these upper and lower limits, so that the limits tend to become narrower and narrower and you have to "play" your way up to the next higher division.
Specifically, the numbers mean: In Intermediate  as off 4th January 2023  approx. 85% of all active players are eligible to play, in Advanced approx. 75%. 61% of all players meet the criteria for both divisions, so they can still decide in which division they want to compete.

When & how will division borders be evaluated afresh?
The division limits are analyzed at regular intervals. As soon as a need for action arises, the limits are adjusted.

Where can I see in which divisions I am allowed to play?
On your personal Playerzone profile you will find an overview in which divisions you are allowed to play. You have to be logged in.